One day your zucchini, cucumber, squash or melons are looking glorious and healthy, and then next day one of them just dies. Flat as a pancake. Wilted, limp, and no heartbeat. What the heck just happened? The culprit is –not squash vine borer, like you thought–but bacterial wilt. Yep, bacterial wilt. So learn why this bacteria is not your friend and how to avoid it like the plague.
In my 10+ years of gardening, I have never lost a plant to bacterial wilt until this year thanks to the cucumber beetles that took up residence in my garden.
And guess what? Don’t let the name of this beetle fool you. Cucumber beetles love your melons, squashes, as well as your cucumbers.
What Does the Cucumber Beetle Look like?
Keep your eyes peeled for this really tiny striped or spotted bug. You can’t kill them since they are so fast. They land on your vegetables and jump off just as fast.
Picture below is the striped cucumber beetle:
Photo by Katja Schulz.
Now the spotted cucumber beetle:
Photo by John Flannery.
How Do Cucumber Beetles Hurt Your Plant?
There are two ways these awful beetles can hurt your plants. They can chew on your seedlings. If you see a plant that looked like multiple shots were fired at your plants, then cucumber beetle may be the culprit.
(Note, flea beetle damage looks similar. However, they tend to eat your eggplants.)
Secondly, as they feed on your plants, they can excrete bacteria, which obstructs water movement in the xylem vessels. This in turn causes the wilt.
Then the adult lay eggs and the larvae pupate in the soil. The larvae attack the roots of the infected plant. When they emerge in August they are contaminated with bacteria upon feeding on the infected plants. The adult beetles overwinter and the cycle repeats itself.
How Do You Know Bacterial Wilt Kill Your Plant?
If the plant wilts completely, then you probably have bacterial wilt. According to the University of Maryland Extension:
“To test for the disease cut a wilted stem, press the side of a knife to the exposed surface and draw it away. If the plant is infected with bacterial wilt disease you may notice white strands of bacterial ooze. You can also immerse a piece of wilted stem in room temperature water and look for a milky discoloration of the water caused by the bacteria.”
Watch University of Purdue Extension’s video illustrating the bacterial ooze on melon.
Note, this is a full proof method since my plants didn’t have the bacterial ooze. According to the University of Kentucky Cooperative Extension Service, this method isn’t as reliable when checking for bacteria wilt in squashes and pumpkins.
Difference Between Squash Vine Borer Damage and Bacterial Wilt.
If a squash vine borer attacks your plant, then part of the vine dies. Also, you can see orange pumpkin excrement coming out of one of your vines.
In my case, the whole zucchini collapsed. I hoped it was just a squash vine borer since I am an expert in digging them out of vines. ( Just call me Doctor Anna.) Unfortunately, in my case, there wasn’t a single site on the zucchini vine that looked like it was attacked by borers.
Just in case you do find the orange goop coming out of the vine, read HERE on how to get that worm out of your vine.
How Do You Protect Your Plants?
Keep the row covers on until the plant blooms. I actually kept my zucchini covered for the longest time but obviously not long enough.
Some people keep the row covers on the whole season, and hand pollinate the blooms.
2. Plant a couple of weeks later than you normally would.
3. Rotate your crops and don’t plant your plants in the same spot for three years. Beetles overwinter in garden debris and awaken in Spring.
4. Delay planting your usual crops by one or two weeks, and plant a trap crop of dark green zucchini at the edge of the garden to lure the beetles. Then destroy the crop. Use the following dark green varieties: Black Jack, Dark Green, Green Eclipse, Seneca, Super Select, and Embassy Dark Green.
University of Massachusetts Amherst suggests using Blue Hubbard squash as a trap crop too.
5. The University of Nebraska-Lincoln Extension suggests to use reflective mulch below your plants since the beetles won’t be able to lay their eggs.
7. Grow watermelons. They aren’t susceptible to this bacteria.
8. Use a foliar spray if more than one beetle is on your plants. (Spray twice a week in the afternoon when beetle infestation is high.) Use Neem Oil, pyrethrum, or Surround WP, which is a kaolin clay-based crop protector.
For chemical applications not intended for organic gardening, read here.
9. Plant less susceptible cucumbers, squashes, and melon. According to Cornell, University of Nebraska and University of Maryland, the following are less susceptible to bacteria wilt.
- Pickling cucumber County Fair has less susceptibility than Dasher II and Calypso cucumbers. Other Less susceptible are Saladin, Gemini, Little Leaf-19.
- Waltham Butternut Squash was less susceptible than Golden Delicious or Blue Hubbard. (I grow this squash.)
- The gourd, Pear Bicolored (Cucurbita pepo) is less affected by the wilt than Turk’s Turban (Cucurbita maxima,) which is severely affected by wilt.
10. Don’t plant your cucurbits next to corn. The spotted beetle feeds on corn as well.
11. At the end of the season, remove weed and debris in the garden to prevent the bugs from overwintering.
Join the Conversation:
How do you fend off cucumber beetles in your garden?
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